Date of Award

Spring 1-1-2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Roger M. Enoka

Second Advisor

Alaa Ahmed

Third Advisor

Robert Mazzeo

Fourth Advisor

Alena Grabowski

Fifth Advisor

Erika Nelson-Wong

Abstract

Human movement is controlled by the dynamic interplay between sensory input and motor output. Varying sensory input, either deliberately through manipulation, or unintentionally via pain or injury, will alter the outgoing motor command and subsequent movement patterns. My dissertation examined these interactions by evaluating sensory-mediated changes in flexibility and assessing movement in the presence of musculoskeletal disorders with associated joint-related pain.

In our first two studies, we explored changes in flexibility with sensory stimulation. First, we assessed the influence of adding transcutaneous electrical nerve stimulation (TENS) or self-massage using therapy balls to a stretching intervention of the plantar flexor muscles on ankle dorsiflexion range of motion, muscle activity, and muscle force. Although there was no influence of TENS, the addition of self-massage doubled the increase in range of motion achieved relative to stretching alone. Gains were more pronounced in less flexible individuals. Surprisingly, self-massage also increased plantar flexor maximal voluntary torque. To further explore the underlying mechanisms, we conducted a follow-up study that evaluated stretching with and without the addition of self-massage. Due to the decline in flexibility across the lifespan, we also included middle-aged adults in the study. The results were similar to our first study. The addition of self-massage increased flexibility gains achieved with stretching alone in both young and middle-aged adults. With the addition of self-massage, middle-aged adults exhibited greater torque increases, which were associated with augmented muscle activity.

In the second two studies, we explored movement patterns as a result of joint-related pain in persons with sacroiliac joint dysfunction (SIJD) and compared them with healthy age-matched individuals. During a sit-to-stand task, individuals with SIJD had greater movement asymmetries including force loading rate when standing up, lower peak hip angle, and delayed onset of muscles key to stabilizing the joint. Furthermore, individuals with SIJD exhibited a significant reduction in the pattern of muscle activity from the painful side gluteus maximus and contralateral latissimus dorsi.

The results of this dissertation underscore the importance of afferent input in modulating range of motion and coordinating movement during activities of daily living.

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